1. Field of the Invention
The present invention relates to a mechanism for electrifying (e.g., grounding), a method of electrifying (e.g., grounding), and a conductive member.
2. Description of the Related Art
Regarding an electrifying mechanism, such as a grounding mechanism, which is used in an electrophotographic image forming apparatus, such as a copying machine, a facsimile, a printer, a plotter, or a multifunction peripheral having these functions, it has been proposed a technique of achieving electrical connection, e.g., grounding, by the use of a static eliminating cloth, a conductive cloth having conductivity and flexibility, or a conductive sheet (for example, see Japanese Patent Application Laid-open No. 2000-48873, Japanese Patent Application Laid-open No. 2007-57945, and Japanese Patent Application Laid-open No. H11-249495 and Japanese Patent No. 3950635).
Japanese Patent Application Laid-open No. 2000-48873 discloses a grounding device for a conductive rotary shaft that is used in a sheet conveying apparatus. The grounding device includes a grounding unit having a core made of an elastic material and a conductive material (a cloth, hereinafter referred to as a “conductive cloth”) formed around the core. A conductive surface of the grounding unit is biased against the surface of the conductive shaft that is rotating, and another conductive surface of the grounding unit is brought into contact with a conductive member that is electrically connected to the grounded frame of the main body of the grounding device, so that the conductive shaft that is rotating is grounded.
Japanese Patent Application Laid-open No. 2007-57945 discloses a technique of achieving the grounding by the use of a static eliminating member, which is provided near a transfer unit to eliminate the static of a recording medium. The static eliminating member uses a static eliminating cloth (conductive cloth) made of a sheet-like conductive fiber aggregate as a base material. The static eliminating cloth is attached to a member and comes into press contact with the member while it is moved in synchronization with the member, so that grounding is achieved.
Japanese Patent Application Laid-open No. H11-249495 discloses a structure including a shaft contact spring (first leaf spring) of a drum grounding plate that comes into contact with an electrical connection shaft by which a photosensitive drum (cylindrical member) is rotatably supported, and two or more grounding spring contact parts (second leaf springs) of cylinder springs and that come into contact with an inner wall of the photosensitive drum, in which the electrical connection shaft and the inner wall of the photosensitive drum are electrically connected to each other (see FIGS. 4 and 20 to 24 of Japanese Patent Application Laid-open No. H11-249495).
Japanese Patent No. 3950635 discloses a static eliminator for a paper conveying apparatus which grounds the static generated from triboelectric charge between a roller and paper and in which a rotary shaft, which supports a paper conveying roller, is supported in a freely rotatable manner at the both ends by supporting members. In this technique, a conductive member for grounding contacts a portion of the peripheral surface of the rotary shaft (which includes an outer circumferential surface and an end face) via a static eliminating cloth, a conductive lubricant is applied to the surface of the static eliminating cloth that faces the rotary shaft made of a metal, and the surface of the conductive member for grounding, on which the static eliminating cloth is attached, has an exposed opposing surface where the conductive member for grounding does not contact the rotary shaft made of a metal (see FIGS. 2, 3, and 6 of Japanese Patent No. 3950635).
However, in the technique disclosed in Japanese Patent Application Laid-open No. 2000-48873, the conductive shaft is pressed against the conductive cloth from above in a vertical direction by the weight of the conveying roller including the conductive shaft, so that electrical connection, e.g., grounding is achieved. Flexibility of the conductive cloth is not actively used in this technique.
In the technique disclosed in Japanese Patent Application Laid-open No. 2007-57945, the static eliminating cloth is attached to a member and comes into press contact with the member by being moved in synchronization with the member. Accordingly, flexibility of the conductive cloth is not actively used like in Japanese Patent Application Laid-open No. 2000-48873.
In the technique disclosed in Japanese Patent Application Laid-open No. 11-249495, a conductive cloth is not used and the electrical connection shaft made of a metal and the first leaf spring, which is also a metal member, slide on each other, so that abrasion occurs on either one or both of the members. For this reason, there have been problems, such as abnormal sound caused by abrasion, poor electrical connection caused by the oxidation of metal, and a large load caused by press contact. As measures against the sliding between metals, a conductive lubricant may be used to solve the above-mentioned problems. However, a conductive lubricant is scraped off at a contact point between metal members as sliding is done many times. Accordingly, although a conductive lubricant is a very effective measure at the early stage of sliding, it is not the fundamental solution.
Since an office machine, which is an electrophotographic image forming apparatus, such as a copying machine, a facsimile, or a printer, is used indoors, it is particularly required that no noise, no abnormal sound, is generated.
Even in the technique disclosed in Japanese Patent No. 3950635, flexibility of the conductive cloth is not actively used like in the techniques of Japanese Patent Application Laid-open No. 2000-48873, Japanese Patent Application Laid-open No. 2007-57945, and H11-249495.
The invention is made in view of the above circumstances and it is an object of the invention to provide a mechanism for electrifying (grounding) a rotator that solves problems caused by the sliding between metals and has a structure which is simple, inexpensive, and environment-friendly, and does not use a conductive lubricant, the mechanism for electrifying (grounding) a rotator being used in any one of an electrophotographic image forming apparatus, an electrostatic recording image forming apparatus, and a magnetic recording image forming apparatus; an image carrier unit, a process cartridge, a belt unit, a fixing unit, a sheet conveying unit, and an image forming apparatus that respectively uses the mechanism for electrifying a rotator; a method of electrifying (grounding) a rotator; and a conductive member (e.g., a conductive cloth).
The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.